The present invention relates to a system and method for writing and reading data to and from traditionally slow erasable disc drives such as optical or magneto optical drives, and more particularly to a system and method for providing streaming recording and playback of audio-video (xe2x80x9cA/Vxe2x80x9d) data and the like to such drives.
Conventionally, device firmware for erasable optical and magneto-optical disc drives such as DVD(trademark)-RAM and AS-MO drives incorporate defect management systems and methods in which spare physical areas or sectors are employed for storing any data that the drivers attempt to write to sectors of the media that are detected as potentially defective. When a defective sector is detected during the use of one of these known systems, the device typically seeks an available spare area where the data can be stored, maintaining the integrity of the data. Thereafter, when reading the media, the device must physically go to the spare area to seek data written there.
A problem encountered in the use of these conventional devices arises when speed becomes important, e.g. when attempting to stream large amounts of data, such as A/V data, live to the storage media. Because each seek operation performed by a conventional device upon detection of a defective area of a storage medium takes additional time, the speed of such devices slows, rendering streaming recording and playback problematic.
A conventional solution to the problem of slow read/write speeds for DVD(trademark)-RAM and AS-MO media and the like resides in providing a buffer between the devices and the system serving as the source or destination of the data. Although this solution represents an improvement over systems that do not employ a buffer, there still exists a discrepancy between the speed required for streaming recording and playback, and the speed at which data can be read from or written to media having defective physical areas. As such, an audio and/or video signal being played back with a conventional buffered system can stutter or freeze when the buffer is exhausted or drops beneath a level sufficient to compensate for the difference between the speed of the drive and that demanded for live streaming by the application.
In order to reduce or eliminate these problems encountered in conventional systems for reading and writing streaming A/V data to traditionally slow disc media such as DVD(trademark)-RAM and AS-MO, it is necessary to reduce or eliminate the delay time consumed by the seek operations of conventional defect management systems.
In accordance with various objects evident to one of ordinary skill in the relevant art from the following description of a preferred embodiment of the invention, a system and method are provided for facilitating the streaming recording and playback of audio-video (xe2x80x9cA/Vxe2x80x9d) data to and from traditionally slow storage media such as DVD(trademark)-RAM or AS-MO media.
A system and method in accordance with the invention controls the writing of data to a storage medium by a storage medium drive. For data categorized as being of a first type, e.g. application data and the like, the data is written to available physical areas on the storage medium. If an attempt is made to write the first type of data to a physical area identified as defective, the writing step includes seeking a spare area on the storage medium to which the first type of data is written. Although this step increases the time required to complete the writing step, it ensures that all of the data is written to the disc and can be recovered. As such, the integrity of the data is maintained.
For data categorized as being of a second type, e.g. A/V data, the system and method of the present invention provides for writing of the data to available physical areas on the storage medium without regard to whether the available areas are defective. Although this step renders the data subject to loss, it increases the speed of the writing step by avoiding time-consuming seek operations whenever a defective area of the media is detected.